Hydraulics

Hydraulics is a technology and applied science that uses liquids to move and control energy. The word comes from Ancient Greek, where "húdōr" means water and "aulós" means pipe. This science combines engineering, chemistry, and other studies to understand how liquids work under pressure.

Hydraulics has been important since ancient times. It is part of fluid mechanics and is used in many areas of science and engineering. By using liquids under pressure, hydraulics helps machines lift heavy weights, control movements, and perform many tasks that need strong force.

One part of hydraulics is called free surface hydraulics. This studies how liquids flow in places like rivers, canals, lakes, and seas. It looks at how water moves in open spaces, such as channels that are not covered. This helps us understand and manage water in nature and in human-made systems.

Overview

Fluid mechanics is the science that helps us understand how liquids move and behave. Hydraulics uses this science to apply engineering with liquids. It focuses on using liquids under pressure to create and control power. This can be seen in many engineering projects and even in the human body, like how blood moves through our veins.

Hydraulics also studies how liquids flow in places like rivers, canals, and lakes. It is like the liquid version of pneumatics, which deals with gases instead of liquids.

Early history

Further information: Timeline of fluid and continuum mechanics

People have used water power for a very long time. In places like Mesopotamia and ancient Egypt, people used water to help grow crops starting around 6000 years ago. They also made clever tools to measure time using water, called water clocks.

The Maya people in Palenque built a special system to make water flow with pressure, shooting it up high for fountains or cleaning. In the Persian Empire, people made amazing systems of canals and dams to control water, including underground tunnels called Qanat that brought water to gardens.

In ancient China, clever inventors used water to power machines. In Sri Lanka, people built huge systems to bring water to farms and gardens. The Greeks built tunnels to move water, and the Romans made big aqueducts to bring water to cities. Later, people in the Muslim world used water to power many machines, like mills for grinding grain and making paper.

Modern history

In the mid 1500s, an Italian engineer named Giuseppe Ceredi improved a water pump called the Archimedean screw. His work helped make the pump better for moving water, and many places in Southern Europe started using it.

Later, in 1619, Benedetto Castelli, a student of Galileo Galilei, wrote a book about how water moves. His ideas helped people understand water better and manage rivers.

Blaise Pascal studied how liquids behave and created the hydraulic press. This machine could use a small force to create a much bigger force, which was very useful. His discoveries are still important today.

In the 1800s, many cities built systems to use water power for machines like lifts and cranes. People like Joseph Bramah and William Armstrong helped make these systems work better. In London, the London Hydraulic Power Company provided water power to many places.

Hydraulic models

After learning the basics of hydraulics, some teachers use a hydraulic analogy to help students understand other topics. For example:

• The MONIAC Computer uses water flowing through special parts to help students learn about money and economics.
• The thermal–hydraulic analogy uses hydraulic ideas to help students learn about heat and temperature.
• The electronic–hydraulic analogy uses hydraulic ideas to help students learn about electricity and circuits.

The rules of how matter behaves, along with how fluids change, create a key link between pressure, how fluid moves, and how much the fluid spreads out. This relationship is shown in a special math form.

When a fluid does not change much in size, any change in pressure needs to come from fluid moving in or out, changing the amount of space the fluid takes up.